1. Field of the Invention
This invention relates to display devices with variable color background.
2. Description of the Prior Art
Commercially available display devices with monochromatic digital readout are capable of displaying data at a relatively fast rate. An operator, however, must evaluate each displayed value by reading it and by performing mental comparisons with predetermined limits. The task is much more complicated when the limits are variable.
A system for measuring radioactivity is described in U.S. Pat. No. 2,643,344, issued on Jun. 23, 1953 to Ian H. McLaren et al. Another systems for measuring radioactivity are described in U.S. Pat. No. 2,648,015 issued on Aug. 4, 1953 to Alexander Greenfield et al., and in U.S. Pat. No. 2,682,000 issued on Jun. 22, 1954 to Joseph F. Clayton et al. Since these three patents are very similar, they are equally authoritative. The system for measuring radioactivity, disclosed in the three patents, includes an analog pointer indicator having three scales, with three associated colored light bulbs, for indicating which scale is applicable for the reading of the measured value. A mechanism for automatic range selection is provided, which is controlled by two solenoids, and which also controls the three associated colored light bulbs. In response to the range selection, one of the light bulbs illuminates the indicator face with a distinctive color to indicate which measurement scale is applicable. After each measurement, the operator must evaluate each measured value to determine its significance, mentally or otherwise.
A digital meter is disclosed in U.S. Pat. No. 2,889,518, issued on Jun. 2, 1959 to Harold R. Hudson et al. The digital meter includes a motor, a wheel counter rotatable by the motor, a potentiometer rotatable by the motor, and a mechanical sampler (vibrator). An unknown voltage is compared, by the sampler, with an instant reference voltage that appears on the wiper of the potentiometer. The motor keeps rotating the potentiometer until the unknown voltage is equal to the reference voltage. The rotation of the motor is then automatically stopped, which also stops the wheel counter, whose position numerically indicates the value of the measured voltage. The decimal point monochromatic lamps are placed between the wheels of the counter. One of the decimal point lamps is illuminated, by manually operated range switch, to indicate by its position the selected measurement range.
The prior art does not contemplate a display device for automatically evaluating the displayed value. The prior art does not contemplate a display device for automatically indicating a significance of the displayed value, by color of the adjacent background area. The prior art does not contemplate a display device for automatically comparing the value of the displayed data with a limit, to determine their relation.
Accordingly, it is the principal object of this invention to provide an improved display device.
It is another object of the invention to provide an improved display device substantially surrounded by a variable color background area.
It is still another object of the invention to provide a display device for automatically evaluating the displayed value.
It is still another object of the invention to provide a display device for comparing the displayed value with a limit to determine their relationship.
It is still another object of the invention to provide a display device for comparing the displayed value with two limits, to automatically determine whether the displayed value lies within the limits or outside the limits.
It is still another object of the invention to provide a display device for visually indicating the significance of the displayed value.
It is still another object of the invention to provide a display device, on which the displayed value is exhibited, for controlling the color of its background area to indicate the result of the evaluation of the displayed value.
It is still another object of this invention to provide a method of controlling the color of the background area of the display device, to indicate whether the displayed value exhibited thereon lies within or without the limits.
It is still another object of the invention to provide a method of simultaneously indicating a displayed value, by a digital indication exhibited on a display device, and its relation to a predetermined limit, by color of a background area that surrounds the display device.
In summary, a method of the invention comprises the steps of receiving data for display, exhibiting a display indication of the data on a light emitting diode display area substantially surrounded by a variable color background area, comparing the value of the data with a limit, and controlling color of the background area in accordance with the result of the comparison. Typically, the background area is illuminated in a first color when the value of the data is less than the limit, and in a second color when the value of the data is greater than the limit.
A display device of the invention includes a light emitting diode display area substantially surrounded by a variable color background area. A device for receiving data for display and for exhibiting them on the display area is provided. A comparator compares the value of the data with a limit and accordingly develops a comparison signal which is used to control the color of the background area, to automatically indicate the significance of the displayed data.
In the prior art measuring and display devices, the measurement is performed after automatically or manually selecting the proper range. The selected range is indicated before the result is displayed either by the color of light shining on the face of an indicator or by the position of an illuminated decimal point lamp. The operator must evaluate each displayed value, mentally or otherwise, to determine its significance.
In stark contradistinction, in the method and apparatus of the present invention, each displayed value is evaluated by automatically comparing it with a limit or limits. The color of the background area is then controlled in accordance with the result of the comparison. As a consequence, the operator does not need to read those displayed values that are exhibited in a color consistent with an insignificant displayed value (typically within the limits), and can concentrate only on those displayed values that are exhibited in a color consistent with a significant displayed value (typically outside the limits).
Accordingly, the invention resides in automatically evaluating the displayed value after it was exhibited, in contradistinction to the prior art, where the measurement range is appraised before the measurement. The invention thus provides a new and unexpected result: the operator does not need to examine those displayed values that are indicated, by color, as being insignificant.